Mental Rotation Test

Each item shows four objects built from cubes. Three of them are the same object seen from different angles; one is not. Pick the odd one out.

The odd object is never obviously different. It is either the same object with a single cube moved, or its mirror image — and a mirror image has the same arms, the same cube count and the same outline, so the only way to rule it out is to turn the shapes over in your head.

30 items, getting harder as the objects grow from five cubes to nine. There is no time limit and no penalty for a wrong answer, but the time is recorded, so both how many you get right and how fast you work are reported. Most people take about 15 minutes.

Items are drawn from a larger pool, so two people rarely see the same set and a retake is a fresh test rather than a memory check.